Diamond abrasive cut-off wheel

ABSTRACT

Segmented diamond abrasive cutoff blades, the segments thereof characterized by their cutting surfaces having substantially uniform linear or lateral serrations.

United States Patent 1191 1111 3,863,401 Schwarzkopf et al. 1 Feb. 4, 1975 1 DIAMOND ABRASIVE CUT-OFF WHEEL 3,305,917 2/1967 Grassmann 143/133 R [75] Inventors: Henry Schwarzkopf, Westchester; 5:22? 51/309 John J. Bouvier, Tonawanda, both i of FORElGN PATENTS OR APPLICATIONS [73] Ass'gnee' Fem corporat'on Cleveland 16,161 6/1902 Sweden 5l/206 P [22] Filed: Dec. 21, 1973 47,220 11/1929 Sweden 51/206 P 200,602 I 1939 S l d 2 (Under Rule 47) wltzer an 1 5/l5 [21] Appl. No.: 427,065

Primary ExaminerOthell M. Simpson Related Apphcamm Data Attorney, Agent, or Firm-Milton L. Simmons [63] Continuation-impart of Ser. No. l53,50l, June 16,

1971, abandoned.

[52] US. Cl 51/206.4, 51/308, 511520195, [57] ABSTRACT [51] Int. Cl B24b 5/00, B24b 3/02 [58] Field of Search 51/209 R, 206.4, 206 P, g e ed diamond abrasive ut blades, the eg- 51/293, 308, 309; 143/133 R; 125/15 ments thereof characterized by their cutting surfaces having substantially uniform linear or lateral serral56] References Cited tions.

UNITED STATES PATENTS 2,777,260 1/1957 Mahlmeister 51/206 P 6 Claims, 7 Drawing Figures PATENIED FEB 4 I975 INVENTORS HENRY P Q-IWARZKOPP JOHN J] Bow/15R F I G 2 ATTORNEY DIAMOND ABRASIVE CUT-OFF WHEEL This application is a continuation-in-part application of co-pending application Ser. No. l53,50l, filed June 16, l97l, now abandoned.

In general, the basic techniques for for manufacturing abrasive wheels of the general class typified by this invention have been well and thoroughly documented in the prior art, best exemplified by prior US. Pat. Nos. 2,818,850, 3,203,774, 3,298,806, and 3,443,343.

Briefly reviewing the prior manufacturing methods used, a circular sheet metal disk, having a discontinuous periphery, formed the central support and drive member, and arcuate segments containing abrasive diamond dust were welded or brazed to the periphery of said disk.

Cutting segments are generally produced separately, and are formed of diamond dust or chips embedded in a heat-setable, or bonded, bronze or nickel copper alloy matrix.

An example of one segment composition would be an admixture containing from 30-70% tungsten carbide, with the balance cobalt and/or nickel to which is added from 2 to 6.5% of diamond dust. A specific satisfactory composition would consist of 40% tungsten carbide, 60% of cobalt as the matrix, containing anywhere from 2 to 6.5% of diamond dust or chips.

Optionally, segments may be produced having a somewhat softer, more readily machineable, nondiamond bearing inner (concave) surface for ease of machining and brazing to a circular support disk.

The segments are usually somewhat thicker than the metal wheel to which they are welded.

The segments of prior cut-off wheels of this general class, have been formed with generally regular, substantially smooth cutting surfaces, for the reason that the actual cutting was accomplished by embedded diamond chips or dust and, as would be the normal expectation, little or nothing would be achieved by any pre-determined cutting surface pattern.

It is therefore an object of this invention to provide a cutting segment having greatly improved cutting efficiency by virtue of its uniformly serrated cutting surface.

It is yet another object of this invention to provide a method of manufacturing the improved cut-off wheel segment of this invention.

Referring now to the attached drawings,

FIG. 1 is a side view of a section of a cut-off wheel produced in accordance with this invention;

FIG. 2 is a cross section taken along the line 22 of FIG. 1;

FIG. 3 is an enlarged view of one of the serrated segments of the wheel depicted in FIG. 1;

FIG. 4 is a side view of a section .of a grinding wheel produced according to this invention having linear serrations;

FIG. 5 is a section taken along the line 5-5 of FIG. 4;

FIG. 6 is an enlarged section taken along the lines 6-6 of FIG. 2, or FIG. 4; and

FIG. 7 is an enlarged view of a serrated segment illustrating added, option serrations at the bottom of the segment.

Utilizing any of the techniques previously known, the segment 1 depicted in FIG. 3 is manufactured, the upper, serrated portion 2 carrying diamond abrasive, the lower section 3 being of a non-diamond bearing, softer more readily machineable metal for brazing to the arbored, steel support and drive disk 4.

The concave face of the segment die or mold may be readily serrated in a transverse direction, the serrations 5 preferably being substantially, uniformly, approximately 90, as shown in FIG. 3, said serrations transferred to the convex face of the segment as a consequence of the forming operation.

As an alternate form of this invention, the serrations may be imparted to the segment linearly, so that their ridges are substantially parallel to the plane of the support disk, as depicted in FIGS. 4 and 5.

It is thus to be understood that the transverse serrations as depicted in FIG. 1 and FIG. 3, particularly in diamond abrasive cut-off wheels, are not in any way to be confused with conventional, metallic saw teeth.

Rather, the serrations are designed, as best illustrated in FIG. 6, to cause certain flat faces of the diamond dust, or chips, 5, to be oriented parallel to one of the inclined faces of the serrations during the pressing and sintering operations.

Using this technique, it will be readily apparent that a much greater percentage of realatively sharp angular points of the diamond dust or chips, will be oriented in such a manner that such points will be more quickly and readily available for immediate and improved cutting when the wheel is initially placed in operation, since the long axes of the diamond particles tend to orient more nearly radially, thus positioning any points outwardly from the center of the wheel, in a position to cut far more efficiently as the binder matrix is sacrificed during operation.

Utilizing prior, conventional, realatively flat arcuate cutting surfaces, it will be seen that the natural tendency is for surface diamond particles, or dust, to be oriented, both at the surface and interiorly, in such a manner that their longest, flatest surface is parallel to the convex surface of the segment; and, in operation, it is therefore likely that a flat surface of a diamond particle will be repeatedly whirled past the article to be cut, providing a much lower degree of cutting efficiency as compared to diamond particles positioned by the serrated segments of this invention.

Stated another way, the difference in cutting efficiency between the segment of this invention, and those which have been heretofore known, may be likened to the difference in abrading efficiency between gouging or abrading with the sharp point of a knife. as compared to attempting to carry out the same operation with the broad, flat side of the knife blade.

From a more quantitative standpoint, the serrated portion of the segment of FIG. 3 may be approximately one fourth the total height of the diamond bearing portion of the segment.

Yet surprisingly, up to one half the life of the segment has been found to reside in the serrated 25% of the segment, based on the total height of the diamond bearing portion. Once the serrations are abraded away, the remaining three-fourths of the segment then cuts with diamonds in the conventional attitude.

Considering that, volume-wise, a 90 serration will only occupy one-half the upper 25% of the diamond bearing portion, half the full cutting life of the entire segment is carried out by 25% 2 12.5% of the diamond concentration of the total segment.

Optionally, the cutting life of a segment may be further extended by forming serrations on both the convex and concave surfaces of the diamond bearing portion of a segment as illustrated in FIG. 7.

In this manner, once the surface serrations are worn away, inverted subsurface serrations become exposed, with their serration-oriented diamond particles providing their increased cutting efficiency.

For best results, I find that an angle of serration of approximately 90 provides the greatest efficiency, although an angle of anywhere from 60 to 1 will provide much improved results.

By serration is meant the more common dictionary definition, i.e., a sharp, pointed, saw-tooth structure such as disclosed in FIGS. 1, 3, 5, 6, and 7 hereof.

The limiting factors to be considered in arriving at the optimum angle are, as the angle gets smaller, there is a certain amount of loss in mechanical strength of the ridges at their base, and if the angle is too great, flatness, as exemplified by the prior art, is approached, thereby reducing cutting efficiency.

Having thus described and illustrated my invention, it is set forth in the following claims which are to be construed in the light of the United States statutes and decisions in such a manner as to give them the broad range of equivalents to which they are entitled.

I claim:

I. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disc, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side surfaces, the improvement of the outer, peripheral cutting surface of said segments being substantially, unidirectionally, uniformly serrated in the form of ridges having sloping faces, and a multiplicity of said diamond particles oriented with a plan thereof coincident with the sloping faces of said ridges.

2. The cutting member of claim 1 wherein said serrations of said segment form an angle of between about 60 to about l 10, and the ridges of said serrations reside in a line substantially normal to the plane of said disk,

.3. The diamond abrasive cutting member of claim 1 wherein said serrations of said segment form an angle of between 60 and about 1 10, and the ridges of said serrations reside in a line substantially parallel to the plane of said disk.

4. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, and the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces.

5. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces, and said serrations of said segments form an angle of between about 60 to about and the ridges of said serrations reside in a line substantially normal to the plane of said disk.

6. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces, and said serrations of said segments form an angle of between about 60 and about 110, and the ridges of said serrations reside in a line substantially parallel to the plane of said disk. 

1. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disc, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side surfaces, the improvement of the outer, peripheral cutting surface of said segments being substantially, unidirectionally, uniformly serrated in the form of ridges having sloping faces, and a multiplicity of said diamond particles oriented with a plan thereof coincident with the sloping faces of said ridges.
 2. The cutting member of claim 1 wherein said serrations of said segment form an angle of between about 60* to about 110*, and the ridges of said serrations reside in a line substantially normal to the plane of said disk.
 3. The diamond abrasive cutting member of claim 1 wherein said serrations of said segment form an angle of between 60* and about 110*, and the ridges of said serrations reside in a line substantially parallel to the plane of said disk.
 4. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, and the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces.
 5. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces, and said serrations of said segments form an angle of between about 60* to about 110*, and the ridges of said serrations reside in a line substantially normal to the plane of said disk.
 6. In a circular, diamond abrasive, segmented cutting member having an arbored, central support and drive disk, a multiplicity of arcuate cutting segments affixed thereto about the periphery thereof, said segments comprising a diamond support matrix having diamond particles therethroughout, and having substantially planular side faces, the improvement of the outer, peripheral cutting surface of said segments being substantially unidirectionally uniformly serrated, the diamond bearing components of said segments are substantially uniformly serrated on both their convex and concave surfaces, and said serrations of saiD segments form an angle of between about 60* and about 110*, and the ridges of said serrations reside in a line substantially parallel to the plane of said disk. 